1. Technical Field
The present invention relates to a lighting unit. More particularly, the invention relates to a lighting unit using a semiconductor light emitting unit as a light source.
2. Background Art
In a lighting unit for a vehicle, for example, a headlamp for a vehicle, it is necessary to form a light distribution pattern with high precision in respect of a safety. The light distribution pattern is formed by an optical system using a reflecting mirror or a lens, for example (see JP-A-6-89601 Publication (Pages 3 to 7, FIGS. 1 to 14)). In recent years, it has been investigated to utilize a semiconductor light emitting unit for a light source of a headlamp for a vehicle.
In the case in which a semiconductor light emitting unit is used as the light source of a lighting unit, it is necessary to satisfy a light amount level required for the lighting unit by maximizing the light emission of the semiconductor light emitting unit. Accordingly, there is a related art problem in that it is necessary to eliminate a factor for intercepting a light emitted from the semiconductor light emitting unit, and furthermore, to prevent luminance from being reduced by heat.
Moreover, the semiconductor light emitting unit is small-sized. For this reason, a light emitting region is narrower than that in a conventional light source. Therefore, there is a related art problem in that it is necessary to maintain a relative position with an optical system with higher precision than that in the conventional art to form a light distribution pattern with high precision.